The present invention relates in general to an apparatus and method for obtaining test cores, and in particular to an apparatus and method for obtaining test cores from concrete and asphalt pavement.
In the paving industry, highway and street authorities and engineers, as well as private engineers on parking lots, require that paving contractors drill out sample cores of pavement after it has been sufficiently cured. These cores are subjected to standard tests to verify the composition and hardness of the pavement. This method is used for both asphalt and concrete paving. The core samples are generally obtained by using a vertical core drill which drills out a core of the material using a tubular diamond-tipped bit driven by a gas or electric drill. The cores generally vary from 4-12 inches in length and are of varying diameters (depending on the preference of the testers).
To test the cores and obtain results that are representative of the pavement in general, it is important to keep the cores intact. Several methods presently used to extract sample cores are: 1) drilling a second identical core hole next to the sample core hole, chipping out the second core hole and then getting under the sample core with a lever and prying it out; 2) driving a pair of rods through the surrounding material and prying out the core; and 3) digging a wedge-shaped hole next to the core and prying it out. These methods are unsatisfactory, however, because the resulting sample core is often not intact. The methods are time consuming, and when the core sample is damaged, the process must be repeated. The problem of obtaining undamaged core samples has been a problem since the beginning of post-paving core testing.